A common method for the recovery of gold and/or silver from a sodium-gold-cyanide solution or from a sodium-silver-cyanide solution involves passing the solution through a sorption tank or column containing one or more fluidized beds of particulate material, such as carbon particles which adsorb the gold and/or silver. Subsequently, the the metal-laden carbon is treated by desorption using other fluids to remove the gold and/or silver therefrom.
A common apparatus used in fluidizing the bed of carbon particles involves providing a bed plate at the bottom of the leaching tank. The bed plate includes a plurality of spaced bubble caps. The solution is pumped through the sorption tank from the bottom to top. As it passes through the bed plate the bubble caps serve to deflect the solution in jet streams down against the upper surface of the bed plate and disburse it through the carbon particles to fluidize them and to provide a large surface area of the carbon particles available to the solution for adsorbing gold and/or silver. However, such structure has certain deficiencies in that the force of the fluid directed by the bubble caps against the bed plate causes erosion thereof and the mixing effect caused by the solution flowing through the bubble caps is uneven, resulting in non-uniform fluidization of the carbon particles and also causes the carbon particles, which are relatively soft, to be abraded by the streams of the solution issuing from the bubble caps so that periodically the carbon particles must be replaced because they are continually being broken down.